The present invention relates to a ladder frame of an engine, and more particularly, to a ladder frame with partition walls defining separate crank chambers.
Generally, an automobile engine includes a cylinder block having cylinders for reciprocally receiving pistons, a cylinder head for installing cam shafts to actuate suction and exhaustion valves, which are installed in the upper portion of the cylinder block, and an oil pan installed in the lower portion of the cylinder block and containing an amount of oil for lubricating the sliding portions of the engine.
The cylinder block is classified in accordance with the length of the skirt into either a long stroke type cylinder block or a short/semi stroke type cylinder block. In the long stroke type cylinder block, the oil pan is directly coupled to the bottom. On the other hand, in the short/semi stroke type cylinder block, a bed plate (the case where the main bearing cap is formed integrally) or a ladder frame (the case where the main bearing cap is formed as a separate member) is interposed between the oil pan and the cylinder block.
In the case where the ladder frame is involved, the cylinder block and the ladder frame form the crank chambers. The oil pan, with an amount of oil therein, is coupled to the bottom of the ladder frame, thereby forming the overall structure of the engine. Accordingly, the ladder frame together with the cylinder block performs a role in ensuring the strength and rigidity of the power train system.
In an engine using a ladder frame, the ladder frame is disposed between the cylinder block and the oil pan. Therefore, the ladder frame is formed such that the respective crank chambers are bottomless, so that the oil drops freely from the cylinder block into the oil pan. Thus, there are no bottoms in the crank chambers, and therefore, the ladder frame is installed by fastening only the edges and the bulkheads thereof to those of the cylinder block respectively.
As a result, during the operation of the engine, the ladder frame is exposed to the vibrations that are generated by the combustion pressure and by the driving of the power train system. Furthermore, vibration is directly transmitted to the oil pan via the ladder frame. Therefore, the conventional engine with a ladder frame is at a disadvantage with respect to noise and vibration.
Further, an oil filter is installed on the ladder frame to filter out foreign materials from the engine oil. In order to install this oil filter, conventionally, a separate installation member (such as a bracket for providing a seat for the oil filter) is used, resulting in the increase in number of the components and process steps.
The present invention provides a ladder frame of an engine, in which the ladder frame between the cylinder block and the oil pan is provided with a bottom wall, thereby dampening the noise and vibrations during operation of the engine. Preferred embodiments of the present invention provide a ladder frame in which installability of the oil filter or an oil cooler is improved. Also oil dropping from the cylinder head drains into the oil pan in a more stable form, thereby reducing air in the engine oil.
In a ladder frame according to an embodiment of the present invention, a plurality of crank chambers are formed within an outer block by forming a plurality of separating walls. A plurality of recessed bearing installation parts are respectively formed on the separating walls and on the walls of the outer block. A plurality of bottom faces are formed on the bottoms of the crank chambers, respectively. A plurality of inclined oil flow faces are also formed on the bottom faces, respectively, with the oil flow faces being inclined downward toward drain holes in the direction of revolution of the crankshaft.
In an alternative preferred embodiment, an outer block has a bottom, two end walls and two side walls. At least three partition walls in the block divide the cavity into at least four crank chambers. Recess bearing installation seats are formed in each of the end walls and partition walls. The bottom also defines inclined oil flow faces in each crank chamber with a low point at one side. At least one crank chamber bottom defines an oil drain hole at the low point. At least one partition wall defines an oil flow passage communicating between the oil drain hole and an adjacent crank chamber. In a further preferred embodiment, at least three crank chambers bottoms define oil drain holes and the partition wall associated with a fourth crank chamber defines an oil flow passages.